brachiosaurus (n.)

before a vowel, brachi-, word-forming element meaning "arm, of the upper arm, pertaining to the upper arm and," from Latinized form of Greek brakhion "arm," perhaps originally "upper arm," literally "shorter," from brakhys "short" (from PIE root *mregh-u- "short"), in contrast to the longer forearm.

element used in forming dinosaur names, from Latinized form of Greek sauros "lizard," a word of unknown origin; possibly related to saulos "twisting, wavering."

Proto-Indo-European root meaning "short."

It forms all or part of: abbreviate; abbreviation; abridge; amphibrach; brace; bracelet; brachio-; brachiopod; brachiosaurus; brachy-; brassiere; breviary; brevity; brief; brumal; brume; embrace; merry; mirth; pretzel; vambrace.

It is the hypothetical source of/evidence for its existence is provided by: Greek brakhys "short;" Latin brevis "short, low, little, shallow;" Old Church Slavonic bruzeja "shallow places, shoals;" Gothic gamaurgjan "to shorten."